This invention relates generally to a three-way valve designed for use with an IV fluid pumping system. Specifically, this invention pertains to a three-way valve which allows continuous fluid flow to a patient during interruption of fluid flow from the original source by permitting sequential access of a second fluid source into the existing fluid flow line with an automatic return to the original source after the pumping of fluid from the second source is completed. This invention is particularly, but not exclusively, useful for the sequencing of fluid from a syringe into a fluid flow pumping system used in an IV infusion.